Electrohydraulic system having a safety shutoff valve for its accumulator



June 9, 1953 A. F. JELINEK 2,641,106

ELECTROHYDRAULIC SYSTEM HAVING A SAFETY SHUTOFF VALVE FOR ITSACCUMULATOR Filed Jan. 5, 1952 ENT0R. Aim-P50 f. (/54 lA/EK.

ATTORNEx Patented June 9, 1953 1 ELECTROHYDRAULIC SYSTEM HAVING A SAFETYSHUTOFF VALVE FOR ITS ACCU- MULATOR Alfred F. Jelinek, Cincinnati, Ohio,assignor to The Cleveland Automatic Machine Company, Cincinnati, Ohio,a, corporation of Ohio Application January 3, 1952, Serial No. 264,815

5 Claims.

Thi invention pertains to improvements in hydraulic systems, especiallysystems for use in conjunction with high pressure hydraulic diecastingmachines.

In machines of the above mentioned type there is provided a hydraulicsystem in which is in corporated a large accumulator bottle charged withnitrogen gas compressed under high prespulls are operated from this sameaccumulator system if desired.

In diecasting machines of the aforementioned type there is required afurnace for melting the metal to be cast. Further, the hydraulic fluidused in the hydraulic system associated with the machine is very lightand also very inflammable especially when coming in contact with an openflame or with the molten metal being provided from the furnace. Incertain cases as when diecasting zinc, the furnace is mounted directlyon the diecasting machines. In other cases where aluminum or similaralloys are used, the furnace is mounted very close to the machine toallow the operator to ladle the metal into the shot sleeve. I'he closepositioning of these furnaces on the machine and to the hydraulic systempresents a definite fire hazard due to the highly inflammable hydraulicoil. In cases Where leaks would develop and when these leaks occur anddirect oil into the open flame of the furnace or into the molten metal,a fire may result. It is therefore important to minimize the amount ofoil fed to such a fire should a leak develop in the hydraulic system.

In most diecasting machine installations a master switch is located at aremote point which allows theoperator to escape from the immediatevicinity of the machine and reach the switch for stopping the hydraulicpump motors of all of the diecasting machines in a particulardepartment. However, de-energizing the pump motors is not the completeanswer to minimizing the amount of oil fed to the fire. If the leak orbreak occurs in the accumulator system, that is, at any point from theaccumulator bottle to the shot or core cylinders, shutting down the mainline switch and the hydraulic pump will not stop the accumulator fromcompletely emptying it entire contents under the influence of theexpanding nitrogen gas. Ordinarily hand operated shutoff valves areprovided at the discharge end of the accumulator bottle. However, suchhand operated valves are not automatic in operation should it benecessary for the operator to immediately remove himself from thepresence of the machine, nor do they act quickly enough that theoperator may close them off before serious fire results.

It is therefore the object of this invention to provide an automaticcontrol valve system in the hydraulic circuit of a diecasting machinefor automatically shutting off discharge from the accumulator bottlewhenever the main stop switch or the main line switch or power supply isotherwise disconnected from the diecasting machine.

Still another object of this invention is to provide a rapidly actingsolenoid control valve system which automatically positively closes offdischarge from the accumulator bottle in the hydraulic system wheneverpower supply is disconnected from the regular hydraulic pump of themachine.

It is still another object of this invention to provide an improvedhydraulic control apparatus for a hydraulic diecasting machine circuitwhich substantially instantly and automatically cuts ofi discharge fromthe accumulator bottle of the hydraulic circuit whenever power supply tothe machine is disconnected.

Further features and advantages of this invention Will appear from adetailed description of the drawing in which the drawing illustrates apreferred form of hydraulic circuit incorporating the improved featuresof this invention.

Referring to the drawing, there is illustrated diagrammatically thebasic electric and hydraulic control apparatus used in connection with amodern high pressure hydraulic diecasting machine .iicorporating thefeatures of this invention. All

of the various supplementary holding electric contacts and otherfeatures of well known character have been eliminated from the diagramso as to direct its subject matter to the essential basic features toshow the environment in which the refinements of applicants inventionhave been applied.

In a high pressure hydraulic diecasting machine there is provided theusual hydraulic pump l which is driven by the hydraulic pump motor 2connected thru leads 3 and the contacts 4 to the power supply lines 5which in turn are connected to the main disconnect line switch fixed tothe power supply leads Ll, L2 and L3. A control circuit is providedutilizing a start push button 1 and a stop push button 8, the latter ofwhich is normally closed at all times whereas the start push button I ispreferably of momentary contact type. When the start button 1 is pressedwith the master switch 6 closed, power is supplied from lead L2 thrulead 9, the stop push button 3, lead 10, the start button 1 and the leadI l to energize the relay coil l2 which in turn is connected to a leadI3 thru a line L3 so as to close contacts 4 and apply power to thehydraulic pump motor 2, suitable holding contacts, not shown, beingprovided to maintain power supply to the motor 2 after the start buttonI has been released.

The fluid pressure pump I driven from the motor 2 receives a supply offluid thru the suction line I 4 from the fluid reservoir I5 andtransmits this fluid under high pressure into the high pressure line Itwhich is connected thru a line I! to the shot cylinder control valve I8.A connection is also made from the line I6 thru the line I9, the checkvalve 26, the line 2I and a pressure regulating valve 22 and a line 23to the shot cylinder control valve I8. The valve I8 is connected thrusuitable lines 24 and 25 to the shot cylinder 26 or to other additionalcylinders as may be required for manipulating the core pulls of themachine. The line H is also connected thru a line 21 to supply pressureto the pilot control solenoid operated valve 28 for the control valveI8. Pilot control lines 29 and 36 are respectively connected to thepilot operating cylinder 3| and 32 for shifting the valve I8 uponmanipulation of the valve 26 in a well known manner. A suitable drainline 33 is connected to a line 34 to return discharge fluid from thevalve 216 to the reservoir I5.

The pilot control valve 28 is operated by the solenoid coils 35 and 36which are connected at one end thru a lead 3! to the lead II so as tobring them into the circuit whenever the start button I is pressed. Theother ends of the coils 35 and 36 are connected thru respective controlswitches or push buttons 38 and 39 thru the leads 46 and M which in turnare connected thru a lead 42 to the power supply line L3.

There is also provided an accumulator system in conjunction with theabove described hydraulic circuit comprising an accumulator bottle 43 inthe upper portion 44 of which there is supplied nitrogen gas thru theline 45, stop cock 46, line 41 and stop cock 43 at asuitable pressure,usually approximately 500 pounds as indicated by a suitable gauge 49.Having thus applied gas under pressure in the bottle 43 the stop cook 46is closed on and the stop cock 48 may be left open to indicate thereading on the gauge 49 or closed during the operation of the machine asdesired. The lower end of the accumulator bottle is connected thru aline 50 a manually operated stop cock SI and a line 52 thru theautomatic shut off valve 53 to the pressure supply line 2! connected asdescribed to the pump I. The valve 53 is provided with a plunger 54which is normally urged to a downward position against the stop surface55 of the pressure chamber 56 by aspring 51 so that its largecylindrical diameter portion 58 of the plunger 54 cuts off the inletport 59 to which is connected the line 52 from the accumulator bottle soas to prevent any escape of hydraulic liquid 60 from the accumulatorbottle 43 under the influence of the gas pressure in the upper portion44 of the bottle 43.

A control valve comprising a valve body liI in which is slidably mounteda plunger 52 which is actuated by a solenoid coil 63 having one of itsleads connected thru a lead 64 to the'lead I I and having its other sideconnected thru a lead 65 to the line L3 so that the coil is energizedwhenever the start button I is pressed and deenergized when the circuitis opened by actuation of the stop button 8 or the main line controlswitch 6 or otherwise disconnecting the power supply from the lines LI,L2 and L3. The valve is shown in the drawing in position when solenoid63 is energized. Fluid pressure from the pump I is connected thru asuitable regulating valve 66 connected to the line l6 and dischargedthru a line 61 to the valve 5|. A discharge drain line 68 is alsoconnected to the valve GI and in turn connected t the discharge drainline 34. A pressure and discharge supply line 69 interconnects the valveBI with the pressure chamber 56 of the valve 53.

The operation of the above described circuit is substantially asfollows:

With the main line switch 6 closed the operator presses the start pushbutton I so as to energize relay coil I2 to close contact 4 to applyelectrical power to the drive motor 2 for the hydraulic pump I, thusstarting operation of the pump and the application of pressure in thepressure supply line I6 as described. At the same time that the startbutton I is pressed relay coil 63 is energized so as to shift theplunger 62 against the bias spring III of the valve EI so as tointerconnect fluid pressure from the pump I thru the line 61 and theline 69 to the pressure chamber 56 of the valve 53 so as to shift theplunger 54 upwardly as shown in the diagram, to interconnect line 52with line 2I so as to connect the accumulator bottle 43 into thehydraulic circuit.

At the same time that the start button I is pressed, thru suitableholding coils, not shown, energy is also now applied to the solenoidcoils 35 and 36 so that when the push button switch 38 is actuated thevalve 28 will be operated so as to apply fluid pressure to the pilotcylinder 32 of the valve I8 and release pressure from the pilot controlcylinder 3| of said valve. In this position fluid pressure from the pumpto the line I6, check valve 26, line 2|, regulating valve 22 and line 23is connected thru line 25 into the forward pressure chamber II of thecylinder 26 so as to cause this cylinder to move its piston I2, pistonrod I3 and connected die apparatus, not shown, toward squeezed position.At the same time gas pressure in the chamber 44 of the accumulatorbottle 43 forces out the hydraulic fluid 60 at a rapid positive ratethru the valve 5I which is in open position, and the valve 53 to theline 2I to supplement the pump pressure I for a very rapid movement ofthe piston I2 to squeezed up position. As soon as the piston reachessqueezed up position the fluid pressure pump then takes over to providethe final high pressure drive for positive positioning of the apparatus.

When the operator presses the control switch button 39 coil 36 of valve28 is thus energized to reverse the process and now apply fluid pressurefrom the pump I to the line 24I I to the return pressure chamber I4 ofthe cylinder 26 to return the cylinder to retracted position. Theaccumulator bottle 43 has the liquid 66 forced back into it to rechargethe pressure in the accumulator by compressing the gas 44 therein fromthe fluid pressure pump whenever the piston I2 reaches either end of itstravel in the cylinder 26 in a well known manner. Thus the accumulatorat all times is provided with a potential pressure discharge of liquid66 so that should a leak develop in any of the circuit beyond the valve53 a serious fire hazard may develop should this liquid come in contactwith the aforementioned heating furnaces necessarily associated withdiecasting machines of this type. Should such a leak develop theoperator need merely press the stop push button 8 or pull the lineswitch 6 whereupon coil 63 of the valve BI is instantly tie-energizedallowing the spring 10 to move the plunger 62 to the left in the diagramclosing off the pressure supply line 61 and connecting the line 69 fromthe pressure chamber 55 of the valve 53 to the drain line 68. Underthese conditions the spring 51 of the valve 53 instantly returns theplunger 54 downwardly so that its cylindrical portion 58 efiectivelyblocks ofi discharge from the line 52 and from the accumulator bottlewithout requiring the operator to laboriously and slowly close themanual valve 5| and thus expose himself to potential fire hazards. Thusthe potential stored energy in the accumulator bottle is kept confinedtherein instantly upon disconnecting of the electrical circuit bymanipulating the stop push button 8 or opening the main line switch 6,both of which may be done from a remote point away from the machine.

While the apparatus herein disclosed and described constitutes apreferred form of the invention, it is also to be understood that theapparatus is capable of mechanical alteration without departing from thespirit of the\invention and that such mechanical arrangement andcommercial adaptation as fall within the scope of the appendent claimsare intended to be included herein.

Having thus fully set forth and described this invention what is claimedas new is:

1. In a hydraulic system having a fluid pressure pump, an electric motorfor driving said pump, a fluid motor connected to said pump to beactuated thereby, a hydraulic accumulator bottle, means for connectingsaid accumulator bottle to said pump and fluid motor, control valve insaid means, and electrical apparatus for connecting a power supply tosaid electric drive motor and said control valve whereby the energizedelectric drive motor and valve causes said pump to operate to supplyfluid pressure to said accumulator and to said fluid motor and whereindisconnecting said power supply causes said accumulator to be shut oflfrom said pump and said fluid motor independent of the fluid pressurefrom said pump.

2'. In a hydraulic system having a fluid pressure pump, an electricmotor for driving said pump, a fluid motor to be actuated from saidpump, an accumulator bottle, means for connecting said accumulator andsaid pump to said fluid motor, including an automatic cutoff valvebetween said accumulator bottle and said pump and fluid motor, springmeans for normally holding said valve in closed position, andelectrically actuated means for holding said valve in open position whensaid fluid pressure pump electric drive motor is energized.

3. In a hydraulic system having a fluid pressure pump, an electric motorfor driving said pump, a fluid motor to be actuated from said pump, anaccumulator bottle, means for hydraulically connecting said accumulatorand said pump to said fluid motor, including an automatic cutoff valvebetween said accumulator bottle and said pump and fluid motor, springmeans for normally holding said valve in closed position, electricallyactuated means for holding said valve in open position when said fluidpressure pump is being driven by said electric motor comprising acontrol valve interconnected hydraulically between said pump and saidcut ofi valve, spring means for normally holding said control valve inclosed position to cut oil fluid pressure from said pump from actuatingsaid out ofl valve to open position, electrically operated solenoidmeans for actuating said control valve when said electric motor fordriving said pump is energized to move said control valve to openposition to apply fluid pressure from said pump to open said out offvalve to thereby hydraulically connect said accumulator bottle with saidfluid pressure pump and said fluid motor.

4. In a hydraulic circuit for a diecasting machine including a hydraulicpump, an electric drive motor for said pump, a fluid motor for actuatingsaid diecasting machine apparatus, an accumulator bottle, and means forinterconnecting said pump said accumulator bottle and said fluid motorin an operative hydraulic circuit including, an automatic cutoff valveinterconnected between said accumulator bottle and said pump and saidfluid motor including a fluid pressure actuating means for moving saidout off valve to open position, a control valve for applying fluidpressure from said pump to said fluid pressure actuating means foractuating said cutofi valve, electrical apparatus for actuating saidcontrol valve to connect said pump to said fluid pressure actuatingmeans, spring means to return said cutofi valve, and switch means forapplying or disconnecting electrical power to said drive motor for saidpump andsaid electrical apparatus for actuating said control valve sothat when said power is disconnected therefrom, said cutoff valveautomatically returns by said spring means to disconnect saidaccumulator bottle from said hydraulic circuit.

5. In a hydraulic control circuit for a diecasting machine having anaccumulator bottle, a fluid pressure pump, an electric drive motor forsaid pump, a fluid motor to be actuated from said pump and bottle, anautomatic cutoff valve connected in the discharge line from saidaccumulator bottle, spring means for normally urging said valve toclosed position, a fluid pressure chamber in said valve for actuatingsaid valve to open position to connect said accumulator bottle dischargeto said pump and said fluid motor, a control valve hydraulicallyconnected to said cutoff valve including a plunger, spring means fornormally urging said plunger to a closed position so that fluid pressurefrom said pump connected thru said control valve to said pressurechamber in said cutofi valve may be shut off therefrom, a solenoidactuating means for said valve plunger operable when energized toconnect fluid pressure from said pump to said pressure chamber in saidcutofl" valve, and electrically operated means for simultaneouslyenergizing or deenergizing said electric drive motor connected to saidfluid pressure pump and said solenoid actuating means for said controlvalve.

ALFRED F. JEIJNEK.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,298,512 Rockwell Oct. 13, 1942 2,566,381 Svenson Sept. 4,1951 FOREIGN PATENTS Number Country Date 911,307 France Mar. 11, 1946

